Elastomeric compositions comprising block copolymers and hydrocarbon oils wherein the copolymer constitutes up to about 30% of the composition with the hydrocarbon oil constituting from about 70% to about 98% by weight of the composition are known in the art as well as methods of preparing these compositions. Examples of such compositions and their preparation are illustrated in U.S. Pat. Nos. 3,676,387 to Lindlof; 3,827,999 to Crossland; 4,176,240 to Sabia; and 4,369,284 to Chen. Various compositions within this class of elastomers have different combinations of physical properties such as hardness, ultimate elongation, temperature stability, mechanical strength, surface tackiness, memory or shape recovery properties, and others. The particular combination of properties which any particular elastomer in this class of compositions will have is not predictable from the starting materials and preparation conditions with a very high degree of certainty. Slight changes in ratios of materials, types of materials used and other factors can produce drastic changes in properties of the final composition.
Radiation cross-linking has been used to modify the physical and adhesive properties of certain copolymer-oil adhesive compositions containing from 50 to 100% copolymer and 0 to 50% extender oil. Examples of such adhesive compositions are shown in U.S. Pat. No. 3,845,787 to Haefele et al and the modification of the properties of such adhesives by radiation curing and cross-linking is illustrated in U.S. Pat. No. 4,151,057 to St. Clair et al and in "Radiation Curing of PSA's Based on Thermoplastic Rubbers" by D. J. St. Clair, Adhesives Age, Mar. 1980, pages 30-36.
The disclosures of the above patents and literature reference are incorporated herein by reference.